Electrical cables used in home or office construction generally comprise a plurality of conductors formed into a bundle and wrapped with a layer of metal armor to protect the conductors against mechanical damage and abuse. Such cables are commonly referred to as Metal Clad Cables and are described in Underwriters Laboratories Inc. Specification Number 1569. In such cables, the conductors generally comprise strands of conductive material, each strand being individually surrounded by a sleeve of insulating material.
Such types of electrical cables often have to perform under adverse conditions. For example, such types of electrical cables must be able to withstand flexing and abuse by the installers and the inhabitants. Further, such types of cables must be able to withstand impact with various items during installation or operation in a home or office.
One known form of electrical cable designed for use in a home or office has a barrier comprising a single layer of non-conductive tape surrounding the bundle of conductors and disposed between the bundle of conductors and the armor sheath. The single layer of non-conductive tape is generally at least 2.0 mils thick to conform to the UL 1569 specification. The layer of tape secures the conductors into a bundle during manufacture and protects the conductors against mechanical damage. However, applicants have determined that under certain impact conditions, a cable with a barrier applied as a single layer of tape can have the armor sheath driven into contact with the conductors. For example, if a force equivalent to a 50 lb. weight dropped from a height of 1 foot (per Section 19 of UL 1569) is applied to a cable with a barrier formed by a single layer of tape, the armor sheath can be driven through the layer of tape and into contact with the conductors. When the metal armor sheath is driven into contact with the conductors, it can short out the cable.